TENS has been used for years as a noninvasive, inexpensive, and safe technique to help reduce acute and chronic pain. See, e.g., Electrotherapy Standards Committee: Electrotherapeutic terminology in physical therapy, Section on clinical electrophysiology and American Physical Therapy Association, Alexandria, Va., 2001, and Rushton D N, Electrical stimulation in the treatment of pain, Disabil Rehabil. 2002 May 20; 24(8):407-15, both of which are incorporated herein by reference.
Typically, the application of a low voltage, low current, mild electrical signal through electrodes placed on skin counteracts other separate nerve signals indicating pain or discomfort. Many studies have supported the gate control theory first described by Melzack et al. in 1965 to explain this physiological response. See, e.g., Melzack R, Wall P D: Pain Mechanisms: A new theory, Science 150:971-978, 1965, incorporated herein by reference.
Briefly stated, pain is elicited when noxious stimuli trigger specific nerve endings in the skin. Pain impulses are then transmitted by small diameter nerve fibers through the spinal cord and to the brain. Gate theory states that there is a gating mechanism in the dorsal horn area of the spinal cord that may act to inhibit the transmission of pain signals to the brain. The gate may be closed by simultaneous stimulation of other larger diameter sensory nerve fibers using non-painful stimuli. Practical application of the gate control theory has lead to widespread use of TENS for pain control. TENS stimulates large diameter sensory nerve fibers with mild repetitive electrical impulses via electrodes applied to the skin. This stimulation acts to close the gate in the dorsal horn and results in the inhibition of pain transmission.
Similarly, vibration therapy is a safe and effective technique, which has long been used to alleviate pain. See, e.g., Vibration Therapy for Pain, Lancet. 1992. Jun. 20; 339(8808):1513-4, incorporated herein by reference. Like TENS, vibration provides another type of non-painful stimulus, which may be used to attenuate the transmission of pain signals by using the gating mechanism described above. Some sensory receptors, like those that sense vibration, are located deeper down in the skin layer and may not be fully stimulated by the superficial current of TENS alone. Vibration therapy and TENS used together may be able to more completely stimulate the sensory receptors found in the skin and result in a more effective blocking of pain signals.
In addition to the physiological mechanism of pain reduction described above, both TENS and vibration stimuli around the procedure site may also act as a form of distraction, making it more difficult to identify exactly where and/or when a painful stimulus occurs.
Commercially available electrodes for TENS therapy come in the form of small electrically conductive patches of different sizes and shapes that are applied directly to the skin and connected to a TENS device via wires. The TENS device is usually a compact self contained unit which is widely available commercially and produces electrical impulses of varying intensities and frequencies based on settings dialed into the unit. Two or more separate electrodes are usually applied to the skin in order to complete an electrical circuit. The electrodes are typically placed at or near the area of pain and used to help alleviate discomfort caused by deeper pain fibers such as those found on muscles and joints.
These types of electrodes have not been specifically designed to induce analgesia of the skin. The multiple separate electrodes are cumbersome to apply and often provide a much wider area of stimulation than is really needed for superficial analgesia. Commonly used electrodes also do not allow access to the underlying skin surface in order to perform procedures and other interventions. It may be highly advantageous if an electrode may deliver concentrated electrical stimulation at or near a potential injection site and at the same time allow access to the site. It may also be advantageous if vibration stimulation may also be delivered through this same electrode to act as additional stimuli for the attenuation of pain.
Painful injections into and through the skin for immunizations, medication administration, blood sugar testing, phlebotomy, IV placement, and the like, are usually done without the use of a local or topical anesthetic. This results in an unpleasant experience for most adults, and may be an extremely traumatic event for children or other sensitive persons. See, e.g., Jacobson R M, Swan A, Adegbenro A, Ludington S L, Wollan P C, Poland G A; Vaccine Research Group. Making vaccines more acceptable—methods to prevent and minimize pain and other common adverse events associated with vaccines, Vaccine, 2001 Mar. 21; 19(17-19):2418-27, incorporated herein by reference.
At times the fear or aversion to these types of procedures may lead to noncompliance of treatments and testing by adults and children alike. A device that reduces or eliminates the pain of these procedures may lead to increased compliance and benefit the overall health of many individuals.
Products to reduce the pain of injections and similar procedures do exist but have significant drawbacks and are not used often because of these limitations. Topical commercially available anesthetic creams such as EMLA (marketed by AstraZeneca) have a slow onset of action, requiring up to 90 minutes to be fully effective. See, e.g., Kundu S, Achar S., Principles of office anesthesia: part II. Topical anesthesia, Am Family Physician, 2002 Jul. 1; 66(1):99-102, incorporated herein by reference.
Ethyl chloride and other similar chemicals, long made available by corporations such as the Gebauer Company, act as a skin refrigerant to numb the skin prior to injections but the effects are short lived and its application is often more painful than the injection itself. Sontra Medical Corporation has a product called the Sonoprep that uses ultrasound to make the skin more permeable to anesthetic creams, but anesthesia still takes a full 5 minutes with this device. Similarly, B. Braun Medical Inc. markets a device called the LidoSite meant to address the pain of injections. This device uses TENS technology to drive topical anesthetics into the skin but still needs at least 10 minutes for full effect.
More recently, Anesiva's Zingo topical anesthetic was FDA approved August 2007 for IV cannulation and venipuncture pain. Anesiva claims effectiveness within about 2-3 minutes but even this is too long to wait considering a typical vaccine shot takes just a few seconds to administer. Another effective technique sometimes employed by experienced practitioners involves manually patting, vibrating, or stretching the skin around the site of injection just prior to a needle stick. This method is also meant to elicit the gating mechanism by using stimuli to mask the pain of injection, but the efficacy is very user dependent. It also leaves only one hand free to perform the injection or other procedure.
Bionix Corporation markets a device called the ShotBlocker, which is pressed onto the skin and uses local pressure to elicit the gating mechanism as described above. This product has multiple blunt tips surrounding a notch and requires one hand to push it against the skin. The fingers must be placed adjacent to the injection site and may be at risk for needle stick injury if unexpected movements occur. It also does not allow much variability in the quality or quantity of stimuli, which may be used to inhibit pain transmission.
Huttner, U.S. Pat. No. 6,902,554, incorporated herein by reference, describes a device which is pressed onto the skin and uses local pressure to elicit the gating mechanism as described above. This device requires one hand to push it against skin, again leaving only one hand available to inject or perform the needed procedure. It also does not allow much variability in the quality or quantity of stimuli, which may be used to inhibit pain transmission.
The following Prior Art references were discovered during a Prior Art search commissioned by applicant. All of these references, as well as the patents and other references cited in the present Specification, are expressly incorporated herein by reference.
Published U.S. Patent Application No. 2005/0149145, (Coulter, George Gary), incorporated herein by reference, discloses a pain reducing apparatus for use during therapeutic injection, (e.g. immunization), which has a current applying device coupled to current generating device for applying nerve stimulating current to electrodes placed around injection location.
Published U.S. Patent Application No. 2004/0015188, (Coulter, George Gary), incorporated herein by reference, discloses a therapeutic injection or sampling device and process which comprises a mechanism for generating electrical output for a Trans Epithelial Nerve Stimulating current and mechanism for applying to patient's body part.
European Patent No. 1699522, (COULTER, GEORGE GARY), incorporated herein by reference, discloses a hemorrhage reducing apparatus for use during therapeutic injection, which has electrodes placed around injection location on skin of patient, where voltage fed to electrodes affects C fibers in skin.
Published U.S. Patent Application No. 2005/0177201, (Freeman, Gary A), incorporated herein by reference, discloses insertion of a probe element through the skin to a penetration depth for treatment, which involves moving the probe element along a penetration depth in a series of incremental movements. In the field of acupuncture, pre-treatment of the insertion area with electrical energy, often in the form of high-frequency waveforms is typically used for transcutaneous electrical nerve stimulation (TENS), is employed to reduce the discomfort of insertion as well as provide optimal placement and treatment.
Published U.S. Patent Application No. 2003/0187490, (Gliner, Bradford Evan), incorporated herein by reference, discloses an annular electrode for neural stimulation, which has an annular outer contact enclosing area, which is several times greater than neural cell structure area.
Published U.S. Patent Application No. 2003/0181960, (Carter, John), incorporated herein by reference, discloses an electrotherapy apparatus for providing therapeutic electric current to a treatment site of a patient, which has a generator providing two pulsing electric alternating currents, a feed electrode and a return electrode.
U.S. Pat. No. 5,776,170 (MacDonald, Alexander John Ranald), incorporated herein by reference, discloses an electrical stimulation analgesia apparatus for electrotherapy, which supplies electrical pulses with rapid rising and falling phases to electrodes on body surface to stimulate analgesia effects in central nervous system.
U.S. Pat. No. 5,366,489 (Burgio, Paul A.), incorporated herein by reference, discloses an anesthesia electrode and applicator assembly for TENS, with active electrodes and return electrodes having a common carrier with a field of pressure sensitive adhesive for adhering electrode to the hand of practitioner or applicator.
U.S. Pat. No. 6,516,226 (Bishay, Jon M), incorporated herein by reference, discloses a percutaneous electrical therapy system, which has an electrode housing, which supports and guides an electrode in a correct way during insertion of the electrode.
U.S. Pat. No. 6,741,889 (Holcomb, Robert R), incorporated herein by reference, discloses an electromagnetic treatment device e.g. for pain and swelling which has an alternating polarity quadripolar array which generates a three dimensional steep field gradient to alter stability of excitable membranes to treat ailments.
Published U.S. Patent Application No. 2005/0089861, (Allen, John J), incorporated herein by reference, discloses lancing to obtain a sample of blood, which involves completely withdrawing the sharpened tip from incision, and drawing blood through the channel to the sensor. Sensor strip may be, for example, a glucose sensor strip which uses electrochemistry to measure the amount of glucose in a bodily fluid, such as, for example, blood or interstitial fluid.
Published U.S. Patent Application No. 2002/0019652, (Da Silva, Luiz B), incorporated herein by reference, discloses a sterile bandage is combined with a TENS device for use in covering a wound and providing electrical stimulation to promote healing and block pain.
U.S. Pat. No. 4,458,696 (Larimore, Franklin C), incorporated herein by reference, discloses a self-adhering TENS electrodes extensible with the skin, comprising body-conformable conductive adhesive and connector layers eliminate dry-out problems.
U.S. Pat. No. 6,871,099 (Whitehurst, Todd K), incorporated herein by reference, discloses a chronic pain e.g. migraine, treating method, involves providing operating power and stimulation parameters to stimulator to generate stimulation pulses based on parameters and delivering pulses to nerves and tissue.
U.S. Pat. No. 5,423,874 (D'Alerta, Mario), incorporated herein by reference, discloses an electronic patch for applying pain reducing electrical energy to a body, which has an electronic circuit formed in a patch for generating and delivering electrical energy through afflicted region on patient's body.
U.S. Pat. No. 5,904,712 (Axelgaard, Jens), incorporated herein by reference, discloses a transcutaneous medical electrode, which uses a grid of conductive arrays, each with selection of electrical connections to sections of arrays.
U.S. Pat. No. 4,177,817 (Bevilacqua, Albert J.;), incorporated herein by reference, incorporated herein by reference, discloses a transcutaneous stimulation pulse electrode assembly, which has two electrolyte-filled chambers between adhesive coated surfaces and electric contacts.
Published U.S. Patent Application No. 2002/0013602, (Huttner, James J.), incorporated herein by reference, discloses a method of controlling pain from surgical injections and minor medical procedures, which involves urging skin engaging surface of pressure member against skin of patient proximate the site.
U.S. Pat. No. 4,289,136 (Rienzo, Sr., Donald D.), incorporated herein by reference, discloses a percutaneous pain alleviation system, which produces variable amplitude right-angled sawtooth pulses at its two electrodes, and has output current control.
U.S. Pat. No. 4,989,605 (Rossen, Joel), incorporated herein by reference, discloses a pain treatment micro-current transcutaneous nerve stimulator, which uses a modulated monophasic sequence of bursts of DC carrier supplied to patient via electrodes.
U.S. Pat. No. 6,907,299, (Han, Shu-Chang), incorporated herein by reference, discloses an electrode for transcutaneous electric nerve stimulator which has a conductive element made of carbon fiber, whose impedance is less than specified value.
U.S. Pat. No. 6,904,324, (Bishay, Jon M.), incorporated herein by reference, discloses a percutaneous probe deploying apparatus to pierce the skin surface using electrodes for use in electrical nerve stimulation to treat pain in tissue.
Published U.S. Patent Application No. 2003/0195599, (Bishay, Jon M.), incorporated herein by reference, discloses a percutaneous probe deploying apparatus to pierce the skin surface using electrodes for use in electrical nerve stimulation to treat pain in tissue.
Published U.S. Patent Application No. 2006/0206164, (Gavronsky, Stas), incorporated herein by reference, discloses a percutaneous electrical nerve-stimulating device for electro-acupuncture, which has a needle/electrode holder including a linear electrode/needle guide channel, and pin electrode connecting needle/electrode to source of electric pulses.
U.S. Pat. No. 4,784,142, (Liss, Saul;), incorporated herein by reference, discloses an electronic dental analgesia method using electrodes on the head and gums to pass an electric wave through patients nerve system to suppress perceived pain.
U.S. Pat. No. 3,620,209 (Kravitz, Harvey), incorporated herein by reference, discloses a reusable vibrating electrical device, which is strapped onto the arm of a patient in order to attenuate the pain of an injection by delivering vibration stimuli around the injection site.